Q: Flying BENEATH Class B/C/D Airspace

[john smith]

The regs say you must communicate, have permission, a clearance, have a
transponder, etc to fly in any Class B/C/D Airspace.
The airspace is generally defined by the airport reference point
altitude and location on the field. For example the definitions state
"from the surface to..."
What requirements are there for flying BELOW the airport surface?
I know several airports with the requisite airspace that are located
above surrounding terrain where it would be possible to fly below the
airport surface.
What say the group?

[Lakeview Bill]

What requirements are there for flying BELOW the airport surface?

A propeller strong enough to dig through the asphalt?



"john smith" > wrote in message
...
> The regs say you must communicate, have permission, a clearance, have a
> transponder, etc to fly in any Class B/C/D Airspace.
> The airspace is generally defined by the airport reference point
> altitude and location on the field. For example the definitions state
> "from the surface to..."
> What requirements are there for flying BELOW the airport surface?
> I know several airports with the requisite airspace that are located
> above surrounding terrain where it would be possible to fly below the
> airport surface.
> What say the group?

[Hotel 179]

"john smith" > wrote in message
...
> The regs say you must communicate, have permission, a clearance, have a
> transponder, etc to fly in any Class B/C/D Airspace.
>> What requirements are there for flying BELOW the airport surface?
> What say the group?

To fly BELOW the airport surface is never recommended. Cumulo granite could
ruin your day:)

I fly out of an airport that is near a Class C with a bottom of 1400....just
stay below that and there's not a problem. Further down the road is a
conglomeration of airspace, but if I stay above 1100, but below 1800.....you
get the picture. This technique is probably more trouble than would be
worth to plan if you were just passing through, but for the local folks it
works well.

Later,

Stephen
Foley, Alabama

[Bob Gardner]

We have just the situation you describe at Seattle-Tacoma Airport...it sits
on high ground adjacent to Puget Sound. On the sectional, just west of the
"all the way to the ground" portion of the Class B, there is a blue square
with "-30" in it, and the legend says "Minus ceiling value indicates surface
up to but not including that value." The surface it refers to is the water.
Ergo, the Class B goes all the way to the water, and you can't fly past SEA
at 500 feet above the water without a Class B clearance.

Paine Field's Class D does not have a similar graphic, but its airspace
extends over Puget Sound and I'm guessing that the same reasoning applies.
Note that AIM 3-2-5 says that Class D "generally extends from the surface to
2500 feet above airport elevation," thus making a distinction between the
surface and field elevation.

Bob Gardner

"john smith" > wrote in message
...
> The regs say you must communicate, have permission, a clearance, have a
> transponder, etc to fly in any Class B/C/D Airspace.
> The airspace is generally defined by the airport reference point altitude
> and location on the field. For example the definitions state "from the
> surface to..."
> What requirements are there for flying BELOW the airport surface?
> I know several airports with the requisite airspace that are located above
> surrounding terrain where it would be possible to fly below the airport
> surface.
> What say the group?

[Ben Hallert]

Assuming you mean 'below the airspace'

Well, for one... there's the mode C veil. 30 miles from the primary
airport located in class bravo, mode C transponders are required and
must be transmitting altitude data.

[Larry Dighera]

On Mon, 27 Jun 2005 23:15:06 GMT, john smith > wrote in
>::

>What requirements are there for flying BELOW the airport surface?

I would think you'd need some digging equipment. :-)

[Fred Choate]

There is also a speed issue when inside the 30 mile radius of the Class
Bravo primary. FAR 91.117 covers that..."No person may operate an aircraft
in the air space underlying a Class B airspace area designated for an
airport or in a VFR corridor designated through such a Class B airspace
area, at an indicated airspeed of more than 200 knots.

Fred


"john smith" > wrote in message
...
> The regs say you must communicate, have permission, a clearance, have a
> transponder, etc to fly in any Class B/C/D Airspace.
> The airspace is generally defined by the airport reference point altitude
> and location on the field. For example the definitions state "from the
> surface to..."
> What requirements are there for flying BELOW the airport surface?
> I know several airports with the requisite airspace that are located above
> surrounding terrain where it would be possible to fly below the airport
> surface.
> What say the group?

[Morgans]

"john smith" > wrote

> What requirements are there for flying BELOW the airport surface?
> I know several airports with the requisite airspace that are located
> above surrounding terrain where it would be possible to fly below the
> airport surface.
> What say the group?

I would say that if you chose to go down that path of picking at cracks in
the definitions, don't be surprised when the crack opens up and sh*ts all
over you. <g>
--
Jim in NC

[Gary Drescher]

"john smith" > wrote in message
...
> The regs say you must communicate, have permission, a clearance, have a
> transponder, etc to fly in any Class B/C/D Airspace.
> The airspace is generally defined by the airport reference point altitude
> and location on the field. For example the definitions state "from the
> surface to..."

The airspace isn't defined by reference to the airport altitude. An airspace
that goes down to the surface goes down to the surface at each point in that
airspace; otherwise, it would say e.g. "airport elevation to 2600" rather
than "surface to 2600".

--Gary

[Chris G.]

My Cherokee 140 won't even do 140 kts (unless I'm out back pushing it
while in a tailwind and descending <g>)



Fred Choate wrote:
> There is also a speed issue when inside the 30 mile radius of the Class
> Bravo primary. FAR 91.117 covers that..."No person may operate an aircraft
> in the air space underlying a Class B airspace area designated for an
> airport or in a VFR corridor designated through such a Class B airspace
> area, at an indicated airspeed of more than 200 knots.
>
> Fred

[Steven P. McNicoll]

"john smith" > wrote in message
...
>
> The regs say you must communicate, have permission, a clearance, have a
> transponder, etc to fly in any Class B/C/D Airspace.
> The airspace is generally defined by the airport reference point altitude
> and location on the field. For example the definitions state "from the
> surface to..."
> What requirements are there for flying BELOW the airport surface?
> I know several airports with the requisite airspace that are located above
> surrounding terrain where it would be possible to fly below the airport
> surface.
> What say the group?
>

The boundary of the airspace is generally defined by the airport reference
point but the altitude at that has nothing to do with the airspace. The
lower limit of a surface area is the surface of the Earth, you'll find it
quite difficult fly below the surface.

[Dave Stadt]

"Ben Hallert" > wrote in message
oups.com...
> Assuming you mean 'below the airspace'
>
> Well, for one... there's the mode C veil. 30 miles from the primary
> airport located in class bravo, mode C transponders are required and
> must be transmitting altitude data.


Kinda true but aircraft not originally built with an electrical system are
exempt.

[Cub Driver]

On Mon, 27 Jun 2005 23:15:06 GMT, john smith > wrote:

>The regs say you must communicate, have permission, a clearance, have a
>transponder, etc to fly in any Class B/C/D Airspace.

No, you don't need a transponder to fly in D airspace. I do it all the
time.



-- all the best, Dan Ford

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[Cub Driver]

On 27 Jun 2005 16:52:23 -0700, "Ben Hallert" >
wrote:

>Well, for one... there's the mode C veil. 30 miles from the primary
>airport located in class bravo, mode C transponders are required and
>must be transmitting altitude data.

Again, not always the case. I have often through the Mode C Veil
around Boston's Logan airport without a transponder. It is legal with
an airpcraft that was built without and has never been equipped with
an electrical system, like the Cub.


-- all the best, Dan Ford

email (put Cubdriver in subject line)

Warbird's Forum: www.warbirdforum.com
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[Cub Driver]

On Mon, 27 Jun 2005 18:27:47 -0500, "Hotel 179" >
wrote:

>To fly BELOW the airport surface is never recommended. Cumulo granite could
>ruin your day:)

Lebanon NH airport is located on a ridge or butte. It would indeed be
possible to fly below the RUNWAY surface, but of course that's not
what the Class D requirement suggests. It extends from the surface of
the ground at any point to 2,500 feet (whatever) above that surface.
So I reckon that in the case of Lebanon, the top of the Class D tuna
can would be rippled: higher where the airport itself is situatated.


-- all the best, Dan Ford

email (put Cubdriver in subject line)

Warbird's Forum: www.warbirdforum.com
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the blog: www.danford.net
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[Cub Driver]

On Mon, 27 Jun 2005 16:51:59 -0700, "Bob Gardner" >
wrote:

>Note that AIM 3-2-5 says that Class D "generally extends from the surface to
>2500 feet above airport elevation," thus making a distinction between the
>surface and field elevation.

Ah! Okay, scratch my presumption that the roof of the Delta airspace
might be rippled :)



-- all the best, Dan Ford

email (put Cubdriver in subject line)

Warbird's Forum: www.warbirdforum.com
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[alexy]

Cub Driver > wrote:

>On Mon, 27 Jun 2005 18:27:47 -0500, "Hotel 179" >
>wrote:
>
>>To fly BELOW the airport surface is never recommended. Cumulo granite could
>>ruin your day:)
>
>Lebanon NH airport is located on a ridge or butte. It would indeed be
>possible to fly below the RUNWAY surface,
Or at least below the altitude of the runway surface.<g>

You can also fly below the altitude of the Leadville runway surface.
The only question is how close a proximity you are to said runway.
--
Alex -- Replace "nospam" with "mail" to reply by email. Checked infrequently.

[Peter Duniho]

"Cub Driver" > wrote in message
...
> [...]
> So I reckon that in the case of Lebanon, the top of the Class D tuna
> can would be rippled: higher where the airport itself is situatated.

The airspace is not "rippled". The maximum elevation is generally 2500 feet
above the *airport*, even as the airspace itself extends to the surface,
wherever that surface may lie.

[Cub Driver]

On Tue, 28 Jun 2005 11:24:21 -0700, "Peter Duniho"
> wrote:

>The airspace is not "rippled". The maximum elevation is generally 2500 feet
>above the *airport*, even as the airspace itself extends to the surface,
>wherever that surface may lie.

Point taken.

I will remember that, the next time I am coasting over the Delta
airspace.


-- all the best, Dan Ford

email (put Cubdriver in subject line)

Warbird's Forum: www.warbirdforum.com
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